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HART Modem ASIC | HT1200M | Page
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7
Table 1 HT1200M Pin Descriptions
Signal
Type
PLCC LQFP
Description
TEST1
input
1
28
Connect to Vss.
TEST2
—
2
29
No connect.
TEST3
—
3
31
No connect.
TEST4
—
4
32
No connect.
TEST5
input
5
1
Connect to Vss.
INRESET input
6
2
Reset all digital logic when low
TEST7
input
7
3
Connect to Vss.
TEST8
input
8
4
Connect to Vss.
TEST9
input
9
5
Connect to Vss.
OTXA
output
10
7
Modulated output transmit and transmit
signal to 4-20mA loop. FSK modulated
HART interface circuit.
IAREF
input
11
8
Analog reference voltage.
ICDREF
input
12
9
Carrier detect reference voltage.
OCBIAS
output
13
10
Comparator bias current.
TEST10
input
14
11
Connect to Vss.
VDDA
power
15
13
Analog supply voltage.
IRXA
input
16
14
FSK modulated HART receive signal
from 4-20mA loop interface circuit
ORXAF
output
17
15
Analog receiver filter input.
IRXAC
input
18
16
Analog receive comparator input.
OXTL
output
19
17
Crystal oscillator output.
IXTL
input
20
18
Crystal oscillator input.
VSS
ground
21
6,20
Ground.
VDD
power
22
21,30 Digital supply voltage.
INRTS
input
23
22
Request to send.
ITXD
input
24
23
Input transmit data. Transmitted HART
data stream from UART.
TEST11
—
25
24
No connect.
ORXD
output
26
25
Received demodulated HART data to
UART.
OCD
output
27
26
Carrier detect output.
TEST12
—
28
27
No connect.
VSSA
ground
—
12,19 Analog ground
